Hi @Anonymous ,
According to your description, you want to delete files/folders that are older than 7 days in OneDrive via MS Flow.
I have made a test on my side, please take a try with the following workaround:
The expression of Compose is: addDays(body('Get_file_metadata')?['LastModified'],7,'yyyy-MM-dd'), add 7 days on the last modified date.
The expression of Condition is: greaterOrEquals(outputs('Compose'),utcNow('yyyy-MM-dd')), judge whether the files are older than 7 days.


Best Regards,
Zhongys